Sources of loss in single-mode polymer optical waveguides

Single-mode optical waveguides based on planar silica have found increasing application in passive optical components such as arrayed waveguide gratings (AWG), couplers, and splitters. Key aspects of these devices are their low insertion losses and relative insensitivity to temperature. Planar polymer waveguides present a complementary technology that is finding deployment in thermally activated components such as thermo-optic switches, variable attenuators and tunable filters. This results from the large thermo-optic effects and low thermal conductivities in polymers that lead to low power, compact and rapid thermal activation. However, the widespread deployment of planar polymer waveguides has been slowed by inability of single-mode polymer waveguides to achieve the low waveguide losses that have been attained in planar silica. In this paper we look at the sources of loss in polymer optical waveguides, assess approaches to reducing losses, and discuss several important loss measurement techniques valuable for evaluation of new polymer materials.